This led to a number of functions failing to work properly and the train being delayed for half an hour at Ladybank in Fife.

A spokesman told the Sunday Post: “We experienced a short delay as a result of a technical issue, but the train was on the move again quickly.”

While Scottish Labour transport spokesman Colin Smyth added: “Many passengers think ScotRail is full of hot air, now it looks like their trains don’t have enough of it.”

Another driver, who contacted The Scotsman, and wished to remain unnamed, stated that the driver of the train was not at fault, they said: “The truth is the driver blew the horn for a level crossing as he is supposed to do. The horn valve jammed open which led to a loss of air.

“This is a very rare fault I can only recall a handful of times this has happened in the last 30 years. However, it was very unfortunate that it should happen on the press run.”